For anyone who comes across this thread at a later date, a packet capture running for several hours from a location prior to the NATing element on my network appears to confirm what @Fae was...

@Fae Thank you for the fast reply. All 3 settings are and have always been disabled, going back many release versions: And the admin account is a local user type: I see no settings in Maintenance...

@Fae What about the Omada Software Controller? Not only does it ignore the option when set to not use the TPLink Cloud, it doubles down by bypassing the local network DNS servers by using hard-coded...